The present invention relates to vehicle interior rearview mirror assemblies and more particularly to a mirror assembly supported from a button secured to the interior of a vehicle windshield.
Heretofore, various rearview mirror assemblies have been proposed. In one form, the interior rearview mirror is suspended from a support attached to the vehicle header adjacent the windshield. These forms of mirror mounts are not completely acceptable. Present vehicle windshield areas, angles of inclination and radii of curvature place certain design constraints on such interior rearview mirror configurations. Aesthetically unpleasing and/or relatively long support arms must be used in order to bring a header mounted mirror into the viewing position of the vehicle operator.
As a result, the majority of rearview mirrors are now attached directly to the windshield of the vehicle. An example of one such windshield mounted mirror may be found in U.S. Pat. No. 3,131,251, entitled MIRROR MOUNTING ASSEMBLY and issued on Apr. 28, 1964, to Ryan. As shown therein, a button is secured by a suitable adhesive to an interior surface of the windshield. The button has a coefficient of expansion similar to that of the windshield glass. A mount defines a shaped recess or cutout which has a complementary configuration to the button. Secured to the mount is an arm to which a mirror case is adjustably attached. The mount supports the mirror case from the windshield when it is slid over the windshield button.
Various governmental agencies have imposed certain standards, test procedures, test conditions, records and recording formats on the manufacture of internal rearview mirror assemblies. The current federal safety standard in the United States is applicable to passenger cars, multi-purpose passenger vehicles, trucks and buses. The stated purpose of the standard is to reduce the number of deaths and injuries that occur when the driver of a motor vehicle does not have a clear and reasonably unobstructed view to the rear. It requires that each passenger car have an inside rearview mirror of unit magnification and that the mirror provide a specified view. The mirror mounting is required to provide a stable support for the mirror. Mirror adjustment by tilting in both horizontal and vertical directions must be provided. Further, if the mirror assembly is located in the head impact area, the mounting is required to deflect, collapse or break away without leaving sharp edges when the reflective surface of the mirror is subjected to a force of 90 pounds in any forward direction which is not more than 45.degree. from the forward longitudinal direction of the vehicle.
Proposed future standards may require the avoidance of any column loading possibility if a mirror assembly is impacted. Such standard would prevent any mirror assembly from including a support which would not collapse or move upon impact to prevent injury.
Another example of a regulation which must be considered by the manufacturer is that promulgated by the European Economic Community (EEC). The EEC Motor Vehicle Regulation sets forth certain standards and testing requirements for interior rearview mirror assemblies. In order to pass a bending test of this regulation, it is necessary that the base or mirror support not leave any "dangerous projection" should the rod or support become detached from its vehicle mount point.
Mirror mounts must be sufficiently rigid to withstand normal loads imposed during use. Mounts must maintain proper operating characteristics throughout the full range of temperatures which might be experienced. Also, as should be apparent, the assembly must be adjustable and meet various governmental regulations. The wide variety of windshield surface areas, angles of inclination and radii of curvature encountered must also be considered in designing any mirror assembly which is adaptable to more than one style or brand of vehicle.
Various proposals have been made for detachably mounting the rearview mirror to the button or other portion of the vehicle in a breakaway fashion. An example of one such mirror may be found in U.S. Pat. No. 4,012,022, entitled BREAKAWAY MIRROR MOUNTING and issued on Mar. 15, 1977, to Tomita. This patent discloses a rearview mirror assembly including a base plate and a supporting arm. The base plate is fastened to the vehicle header immediately above the windshield. The supporting arm defines an abutting surface from which a configured projection extends. The projection is received with a corresponding configured opening defined by the base plate. Lateral protrusions on the projection are engaged by resilient strips defined by the base plate.
Another prior windshield-mounted interior rearview mirror including a breakaway feature may be found in French patent publication No. 2,229,233. The rearview mirror disclosed therein includes a mirror case support arm of a rigid material and a base part or button which is attached to the vehicle windshield. A separate resilient clip secures the support arm to the base part. The clip is fabricated from a plastic material and the support arm is firmly secured to the button through the plastic clip. Some of the engaging surfaces of the clip are flexible so that the clip and support arm can be disengaged from the button upon impact to the mirror case. The assembly includes essentially three parts.
A still further example of a breakaway mirror assembly includes a one-piece plastic support bracket and a rigid, substantially inflexible button. The bracket includes a support arm and an attachment means which is integral therewith. The button is formed from stamped or die cast metal and is securely bound directly to the inside surface of the vehicle windshield. The button has a linear coefficient of thermal expansion which is close to that of the glass. Repeated temperature cycling or heating and cooling of the windshield and/or button will not induce strains which would subsequently weaken the adhesive. The button defines a recess bordered by a pair of opposed, inwardly facing grooves. The bracket defines a pair of outwardly extending tongues which are engaged by and slide into the grooves of the base part. The bracket also includes bearing surfaces which are pressed slightly against complementary bearing surfaces of the button. These surfaces assist in securing the attachment of the bracket to the button. The bracket is assembled to the button from a point above the button and immediately below the vehicle header. When the bracket sustains an impact of predetermined magnitude, the lower end of the bracket at its attachment area will in effect pivot about a bottom wall defined by the button. The pliable tongues will release from the grooves of the button.
A need exists for an interior rearview mirror assembly which is capable of satisfying the various design criteria, is configured to be usable in the majority of vehicles which have varying windshield areas, angles of inclination and radii or curvature, which will readily break away from the mirror mount when subjected to an impact of predetermined magnitude, which is aesthetically pleasing and capable of high volume production at reduced manufacturing cost from that heretofore experienced.